1. Field of the Invention
The present invention relates to a package of semiconductor device, and more particularly to a package of semiconductor device electrically connected with a flexible printed circuit board.
2. Description of the Prior Art
Ever increasing industry demand for smaller and smaller electronic packages with a low profile, higher area density and increasing number of input/output connections (I/Os) has led to increasing demand for the chip scale package. Use of such packages may be found in small portable products, such as cellular phones, pagers, and the like. Moreover, a flexible printed circuit board (FPC) is widely used in view of the freedom of packaging form and the space saving. A wire bonding is frequently used when a high-density package is required or a package space is limited.
FIG. 1 is a schematic configuration of a known package of an image sensor device incorporated with a handset. The package of the image sensor device has a silicon substrate 101 having at least one pad 105 on a surface thereof and an image sensor device 102, such as CMOS (Complementary Metal-Oxide-Semiconductor) sensor, LCOS (Liquid Crystal-On-Silicon), on the surface. A glass plate 103 is placed above the surface of the silicon substrate 101 having the image sensor device 102. The glass plate 103 is used for preventing airborne dust or other particles from adhering unto the image sensor device 102, causing the image sensor device 102 damage. The glass plate 103 is attached unto the silicon substrate 101 by adhesive material 104. The silicon substrate 101 is placed on a printed circuit board 100, and the pad 105 is connected with an I/O terminal of the printed circuit board 100 via a metal wire 106 by wire bonding. A lens housing 107 enclosing the whole silicon substrate 101 is held on the printed circuit board 100. A lens set 108 is positioned above the glass plate 103 and held by the lens housing 107. A flexible printed circuit board 109 is attached onto the printed circuit board 100. In general, the fingers of the leads of the flexible printed circuit board 109 are bonded to a contact portion of the printed circuit board 100. The flexible printed circuit board 109 is electrically connected to a main board of the handset. The image sensor device 102 captures image signals, and transfers the image signals to electric signals. Then, the electric signals are transmitted to the flexible printed circuit board 109 via an interface, i.e., the printed circuit board 100, and then transmitted to the main board of the handset.
The package of the image sensor device of FIG. 1 is troublesome and bulky. However, the flexible printed circuit board 109 cannot be directly attached unto the silicon substrate 101 due to the configuration of the image sensor device. It is necessary to form a gold bump on the pad 105 of the silicon substrate 101 before the fingers of the leads of the flexible printed circuit board 109 are to be electrically connected with the pad 105. However, the gold bump cannot be electroplated on the pad 105 of the silicon substrate 101 because the glass plate 103 has been covered on the silicon substrate 101. When the silicon substrate 101 is uncovered with the glass plate 103, the image sensor device 102 is easily subjected to damage by the particles during the process of the package, and resulting in a low yield. Therefore, the flexible printed circuit board 109 cannot be directly attached unto the silicon substrate 101 in view of the configuration of the package of the image sensor device.
Accordingly, it is the intention to provide a package method of a semiconductor device, which can overcome the drawbacks of the prior art.